Calender for embossing and compacting a textile web

ABSTRACT

An apparatus for embossing and compacting a textile web has a calender with a body having a surface. An array of embossing formations project from the body surface and each have an outer face directed away from the body surface and formed as a narrow strip pressable into the web.

FIELD OF THE INVENTION

The present invention relates to a calender. More particularly thisinvention concerns such a calender roll for embossing and compacting atextile web.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing:

FIG. 1 is largely diagrammatic end view of a calender assembly accordingto the invention;

FIGS. 2 a and 2B are detail views illustrating bumps in accordance withthe invention;

FIGS. 3, 4, and 5 are top views of further calender bumps according tothe invention;

FIG. 6 is a section through another calender bump according to theinvention;

FIGS. 7 and 8 are small scale top views of calender formations inaccordance with the invention;

FIGS. 9 and 10 are sections illustrating calender bumps according to theinvention;

FIG. 11 is a top view of a portion of a calender roll with bumpsaccording to the invention;

FIGS. 12 and 13 are top views of bumps according to FIGS. 4 and 3,respectively;

FIG. 14 is a schematic side view illustrating the manufacture of aprior-art three-layer textile web;

FIG. 15 is a top view of the prior-art web of FIG. 14; and

FIG. 16 is a view like FIG. 15 of the web according to the invention.

BACKGROUND OF THE INVENTION

A standard calender roll or calender belt for embossing and/orcompacting textiles, nonwoven fabrics, in particular spun-bonded fabricsand/or paper materials, has an outer surface provided with bumps,elevations, or flat embossing formations that project outward from thesurface of the calender roll or belt. At least a portion of the surfacesof the bumps or of the embossing formations are pressed duringembossing/compaction into the web being treated.

Such a roll for compacting a nonwoven textile web by means of heatand/or solvents is known from German utility model 83 20 960. It hasribs on its outer surface bumps or ribs that project outward. The bumpshave inclined flanks and expand toward their bases. The flanks of thebumps have two portions with different flank angles. A portion closer tothe outer end has a more acute angle to a centerline than the portioncloser to the base. The aim of the broader bases of the bumps is toenable good heat transfer to the flat upper ends of the bumps, therebyallowing the rolls to be used over a long period of time. The end facesof the bumps are rectangular. The outer faces are flat and continuous.One disadvantage is caused by the punctiform and planar, i.e. completelyflat, design of the bumps, so that during water-jet needling the fibersor pulp is completely washed off in the region compacted by the endfaces.

It is also generally known to use calender rolls for calendering orcompacting textiles, nonwoven fabrics, and in particular spun-bondedfabrics. The known calender rolls are provided with bumps for thispurpose. However, these are not adequate for compacting all the fibers,in particular short fibers on the surface of the textiles, so that nofibers project from the surface of the nonwoven fabric and the pillingeffect is avoided.

As shown in FIGS. 14 and 15, in a standard prior-art process a lower web10 is advanced in a travel direction 13, a mass of fibers 9 aredeposited on it, and an upper web 8 is laid atop the fibers 9. Presumingthat the three-layer assembly is then calendered together with thesystem such as shown in the above-cited German utility model thatpresses an array of small flat areas into the laminate, the subsequentwater-jet needling as done at 11 will wash out the filaments in theembossed areas and cause them to bunch up therebetween as shown at 12.Obviously this is an inferior product since some areas will have nofibers 9 and others will have too many fibers 9.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide animproved calender for embossing and compacting a textile web.

Another object is the provision of such an improved calender forembossing and compacting a textile web that overcomes the above-givendisadvantages, in particular that eliminates these disadvantages and,among other things, produces a two-layer nonwoven fabric containing pulpor fibers and a spun-bonded fabric as the outer layer, or a three-layernonwoven fabric containing pulp as intermediate layer and a spun-bondedfabric as outer layers, where the pulp is not washed away at theembossed locations during water-jet bonding, so that fiber-free spotsare no longer formed at these location which, as has been the caseheretofore, give the surface of the nonwoven fabric an irregularlypatterned appearance

Another object of the invention is to design the calender roll forembossing and/or compacting textiles, nonwoven fabrics, in particularspun-bonded fabrics, in such a way that when such calendered textiles orspun-bonded fabrics are used, no fibers or loose filaments project fromthe surface of the textiles. The fibers are no longer washed away duringwater jet bonding, so that no fibers-free points or faces are formedwhich, as has been the case heretofore, gives the surface of thenonwoven fabric an irregularly patterned appearance. In addition tothese visual characteristics according to the invention, the usecharacteristics are also significantly improved due to a more uniformabsorption rate.

SUMMARY OF THE INVENTION

In an apparatus for embossing and compacting a textile web, a calenderhas according to the invention a body having a surface, and an array ofembossing formations projecting from the body surface and each having anouter face directed away from the body surface and formed as a narrowstrip pressable into the web.

With the apparatus using the calender of this invention no loose fibersor filaments appear on the surface of the nonwoven fabric. In addition,such a strip-shaped outer face is simple and economical to manufacture,while the very good heat transport through the embossing formationsaccording to the invention to their outer faces is maintained due to theadvantageous shape.

To this end, it is advantageous for the outer faces of the formations tobe smaller than the remaining outwardly directed portions of the bump,or of depressions provided in the outer faces. A low-wear embossingformation is obtained as a result of this design. Use of centraldepressions ensures that no loose fibers or filaments appear on thesurface of the nonwoven fabric, even in the region where the formationsengage and emboss the web.

The water-jet bonding is advantageously performed before calendering,since calendering is not meaningful after the water jet bonding due tothe fact that the fusible fibers acts as a separating layer between thetwo layers.

For this purpose it is advantageous when the distance between the outerend face and the surface of the calender roll is greater than theremaining portion of the outwardly directed face of the depression inthe embossing formation. Such a depression is very easily manufactured.

It is also advantageous for the depression in the embossing formation tobe designed in the shape of an internal cavity whose surface tapers intothe embossing ridge or gradually merges into the surface of theembossing ridge, that is part-spherical. The rounded edges formed atthis location ensure that the nonwoven fabric is not subjected tointense stress during processing.

In a further embodiment of the invention, it is advantageous for theoutwardly directed surface of the indentation or cavity in the embossingformation to be recessed with respect to the outer end face of theembossing formation, in the direction of the surface of the calenderroll or the calender belt. This also prevents material accumulation fromoccurring at certain locations on the nonwoven fabric.

It is also advantageous for the bumps to have outwardly tapered lateralsurfaces running at right angles or in an inclined manner with respectto a surface of the calender roll, and at least one outer, outwardlydirected closed outer end face that encloses the indentation. The closedouter end face may form a closed circle or any given shape, so thatafter the calendering no loose fibers or filaments appear on thesurface.

In a further embodiment of the invention, it is advantageous for thebumps to be composed of a truncated pyramidal body that is provided witha round, oval, or polygonal base and/or the outer outwardly directedround, oval, or polygonal surface in which the indentation is provided,the indentation being enclosed by the embossing ridge that may havelateral openings or passages at one or more locations so that the fiberscannot be rinsed away to the side in large quantities, but instead arerinsed to the side only in the region of the outer end face, i.e. thestrips in the embossing formations, in particular in the center of theembossing formations. As a result, large fiber-free regions are nolonger formed in the nonwoven fabric.

Thus, during calendering of the nonwoven fabric a satisfactory bondingof the fibers, i.e. the short filaments, to the upper and lower nonwovenfabric is achieved in a simple and more economical manner. Since theembossing formations or lines as viewed from above have an annulardesign, or a circular or similar cross-sectional shape, during waterneedling there is no displacement of the fibers in the region of theembossing formations; i.e. the fibers are not horizontally dislocated orlaterally shifted, particularly since during needling of the nonwovenfabric the water jet can also penetrate through the calenderedlocations, since these locations on account of their annular design areprovided with an opening through which the water jet can enter, impingeon the fibers, and stitch-bond same to the upper and/or lower layer.

According to another illustrated embodiment, it is advantageous that thecalender roll or calender belt for the apparatus for embossing and/orcompacting textiles, nonwoven fabrics, in particular spun-bonded fabricsand/or paper materials, has bumps or flat embossing formations on itssurface that are outwardly oriented or upright relative to the surfaceof the calender roll, at least a portion of the surface of the bumps,i.e. calender elevations, being designed as a outer end face, and thatthe outer end face is a narrow, oblong, linearly extending embossingridge that is positioned in such a way that, at least together with anadjacent or adjoining embossing ridge, it completely or at leastpartially encloses a recessed face that is formed by the surface of thecalender roll or calender belt, or by an indentation provided in thebump. Such a embossing ridge prevents the described washing away of thefibers in a particularly advantageous manner.

According to one refinement of the invention, another possibility isthat the outer end face of the embossing ridge extends on a line that asviewed from above forms a circle, rectangle, oval, or a polygonal,undulating, or meandering shape, or a flat pattern. In this manner, in avery small region of the nonwoven fabric outer end faces are produced;i.e., compaction of the nonwoven fabrics is achieved. In this case thebase is identical to the surface of the calender roll.

It is also advantageous when the embossing ridge is composed of uprightor band-shaped bodies on the surface of the calender roll or calenderbelt, which viewed from above form a straight and/or a nonstraight line.Various embossings are thus obtained in the nonwoven fabric in a simplemanner. Although this hardly has a measurable influence on thewashing-away effect, it provides an important possibility for designinga more attractive appearance and for imparting various products with anindividual character.

It is of particular importance for the present invention that the bumpsinclude the surface that contains the flat, outwardly directedindentation whose face is approximately parallel to the base of the bumpor the surface of the calender roll.

For this purpose it is advantageous when the base of the bump isslightly larger than the outward outwardly directed face thereof. Theuniformity of the fibers as well as the visual character of the productmay be modified by means of the ratio of these two faces.

According to one refinement of the invention, a preferred possibility isfor the base of the bump to be between 1.2 and 3 times larger than theoutward outwardly directed face thereof.

It is also advantageous when the distance between centers of twoadjacent bumps is 2 to 5 times larger than the average diameter of thebody of the bump.

It is also advantageous when the lateral surface of the bump, which istapered or inclined or also straight, forms an angle with the base thatis between 0° and 60°, in particular between 15° and 45°.

Last, according to one preferred embodiment of the approach according tothe invention a two-layer nonwoven fabric containing fibers and aspun-bonded fabric is laid on a deposition belt as an outer layer, or athree-layer nonwoven fabric containing fibers as intermediate layer anda spun-bonded fabric as each outer layer, is calendered after bonding bymeans of a water jet and/or after a drying process by use of thecalender rolls having the bump according to the invention.

It is of particular importance for the present invention that the bumpsare provided on the surface of the calender rolls in such a way that thebonding is performed in a pattern that is round, oval, diamond-shaped,polygonal, linear, and/or having broken lines, or in the shape of apattern or surface pattern.

SPECIFIC DESCRIPTION

As seen in FIG. 1 a calender apparatus 1 for embossing and/or compactingtextiles, nonwoven fabrics, in particular spun-bonded fabrics and/orpaper materials, comprises a two spacedly adjacent calender rolls 2 thatmay be positioned by hand. Numerous uniformly spaced embossingformations, referred to below as bumps 5, are provided on a surface 3 ofthe calender roll 2.

According to FIG. 2, the bumps or elevations, i.e. embossing formations,5 may each comprise a truncated pyramid whose base 7 has a diameter d2that is approximately twice as large as an outer diameter d1 of asurface 6 having a outer end face 6.1. The sloping side surface 4 of thebump 5 forms an angle α with the base that may be between 0° and 140°.The angle α is preferably between 90° and 130°.

According to FIGS. 2 a, 2 b, and 3 through 6, each bump 5 or itsoutwardly directed face 6, may also be provided with an internaldepression or cavity 6.2, thereby forming the annular embossing ridge6.1. According to FIGS. 2 a, 2 b, and 6 the recessed center surface 6.2may have different depths, and according to FIG. 6 may be modified sothat a circular cylindrical body is produced.

The embossing ridge 6.1 is illustrated in FIGS. 2 through 6 withreference to various examples. According to FIGS. 3 and 13, theembossing ridge 6.1 may also be open on one side, giving it a C-shaperather than the O-shape of FIGS. 4 and 12. The embossing ridge may alsobe designed strictly as a straight or undulating line that may be brokenat several locations.

The flat surface 6 of each bump 5 extends approximately parallel to thebase 7 of the bump 5.

According to the invention the base 7 of the bump 5 may be between 1.2and 3 times larger than the outwardly directed face 6 thereof.

In addition, the distance between centers of two adjacent bumps 5 may be2 to 5 times larger than the average diameter of the body of the bump.

As previously mentioned, according to a further illustrated embodimentcorresponding to FIG. 6 the body of the bump may also have thevertically extending surface 4, resulting in a cylindrical shape.

A diameter d3 of the bump 5 is only slightly larger than a diameter d4of the recessed surface 6.2, so that a relatively narrow embossing ridge6.1 is formed. The width of the embossing ridge 6.1 is between 0.3 and0.8 mm. A height h of the bump 5 may be between 0.01 and 3 mm.

The two- or three-layer composite material is made by laying asdescribed with respect to the prior art and shown n FIG. 14 a lowerlayer 10 on a deposition belt 15 and a hopper 16 or the like for loadingfibers 9 onto the lower outer layer 10. After calendering, drying, andoptional application of a top outer layer 8 the composite is subjectedto water-jet needling 11.

In FIGS. 7 and 8 the outer end face 6.1 is a narrow, oblong, linearlyextending embossing ridge that is positioned such that, at leasttogether with an adjacent or adjoining embossing ridge 6.1, itcompletely or at least partially encloses a recessed face 6.2 that isformed by the outer surface of the calender roll 2 or calender belt, orby an indentation 6.3 provided in the bump 5. In FIG. 7 the embossingridges form a rectangular shape, and in FIG. 8 form a slightly elongatedparallelogrammatic shape.

The outer end face of the embossing ridge 6.1 extends on a line that asviewed from above according to FIGS. 7, 8, 12, and 13 forms a circle,rectangle, oval, or a polygonal, undulating, or meandering shape, or aflat pattern. Only a few embodiments are illustrated in the drawing. Theembossing ridge 6.1 forms an upright or band-shaped body on the surfaceof the calender roll 2 or calender belt, which in the view from aboveforms a straight (FIG. 7) or a non-straight (FIGS. 8, 11, 12) line.

According to FIGS. 7 through 10 and FIGS. 12 and 13, the bumps orelevations 5 include the surface 6 that contains the flat, outwardlydirected indentation 6.2 that is approximately parallel to the base 7 ofthe bump 5 or the surface of the calender roll 2.

In FIG. 16 the embossing formations pressed into the composite web areillustrated in view from above, similar to that shown in FIGS. 1 through2 b and FIGS. 3 through 6, where some embossing formations are closedand some are open on the side. Use of the advantageous design of theembossing ridges 6.1 ensures that the fibers 9 is not washed away as inFIGS. 14 and 15 when the nonwoven fabric according to 14 is bonded bythe water needling 11. According to FIG. 16 a uniformly distributedfibers intermediate layer 9 is obtained.

As previously mentioned, the distance between the center axis of twoadjacent bumps 5 may be 2 to 5 times larger than the average diameter ofthe body of the bump. According to the examples in FIGS. 7, 8, and 11through 13, the outer end face of the embossing ridge 6.1 extends on aline that as viewed from above forms a circle, rectangle, oval, or apolygonal, undulating, or meandering shape, or a flat pattern.

In addition, the bump 6 may include the flat, outwardly directed surface6 containing the indentation 6.3, whose face is approximately parallelto the base 7 of the bump 5 or the surface 3 of the calender roll 2.

1. In an apparatus for embossing and compacting a textile web, acalender comprising: a body having a surface; and an array of embossingformations projecting from the body surface and each having an outerface directed away from the body surface and formed as a narrow strippressable into the web.
 2. The calender defined in claim 1 wherein theformations are substantially uniformly spaced over the body.
 3. Thecalender defined in claim 2 wherein the body is a roller adapted to berotated about a central axis, and the body surface is substantiallycylindrical.
 3. The calender defined in claim 1 wherein each formationhas a base at the body surface that is wider than the respective outerface.
 4. The calender defined in claim 3 wherein each base is between1.2 and 3 times wider than the respective end face.
 5. The calenderdefined in claim 1 wherein the outer faces are generally C- or O-shaped.6. The calender defined in claim 5 wherein the outer faces aresubstantially circular.
 7. The calender defined in claim 5 wherein theformations are frustoconical bumps.
 8. The calender defined in claim 5wherein the formations are cylindrical bumps.
 9. The calender defined inclaim 5 wherein the outer faces are oval.
 10. The calender defined inclaim 5 wherein each formation had a center recessed toward the bodysurface from the respective outer face.
 11. The calender defined inclaim 10 wherein the centers are generally part spherical.
 13. Thecalender defined in claim 10 wherein the centers extend substantiallyparallel to the body surface and to the respective end faces.
 14. Thecalender defined in claim 1 wherein the formations are bumps and arespaced apart on the body surface on center by a spacing equal to between2 and 5 times a diameter of the end faces.
 15. The calender defined inclaim 1 wherein the formations project between 0.01 and 4 mm from thebody surface.
 16. The calender defined in claim 1 wherein the formationshave side flanks inclined at an angle of between 15° and 45° to the bodysurface.
 17. The calender defined in claim 1 wherein the formations arean array of ridges.
 18. The calender defined in claim 1 wherein theridges cross and define an array of recessed lands.
 19. The calenderdefined in claim 1 wherein the apparatus further comprises means forforming a two-layer fleece having at least one outer layer and a mass offibers thereon; and means for passing the fleece past the calender whilepressing the formations into the fleece.
 20. The calender defined inclaim 19 wherein the apparatus further comprises: means for water-jetneedling the fleece upstream of the calender.